Since photographic light-sensitive materials are generally composed of an electrically insulating support and photographic layers, static electric charges are frequently accumulated in the step of preparing the photographic light-sensitive materials and during their use by contact friction between the surfaces of the same or different kinds of material or by subjecting to separation. The accumulated static electric charges cause various troubles. The most serious trouble is that the static electric charges accumulated prior to development processing are discharged so as to expose the light-sensitive emulsion layers to light, whereby dot spots or branched or feathery linear specks are formed upon development processing of the photographic films. This phenomenon, which is called static marks, greatly damages the value of photographic films and, in some cases, the value is entirely lost. For example, in the case of medical or industrial X-ray films, it is easily understood that such a phenomenon can bring about a misdiagnosis. In the case of color photographic light-sensitive materials, momentous recollections can be ruined. This phenomenon is a very troublesome problem because it is found for the first time upon development. Further, the accumulated static electric charges induce secondary problems, for example, dust adheres to the surface of the films or a uniform coating cannot be obtained.
Such static electric charges are frequently accumulated during the preparation or use of the photographic light-sensitive materials as described above. For example, in the step of preparation, they are generated by contact friction between the photographic film and a roller or by separation of the emulsion face from the support face in the step of winding and rewinding of the photographic films. In the finished products, they are generated by separation of the emulsion face from the base face in the case of conducting exchange of the winding operation of the photographic film or by contact or separation of the X-ray film with or from machine parts or fluorescent sensitizing paper in an automatic camera.
In color negative films and color reversal films, they are generated by contact with or separation from rollers or bars made of rubber, metal, plastic, etc., in the camera or the bonding machine or automatic developing machine in the development shops.
In addition, they are generated by contact with packing materials, etc. Generation of static marks on photographic light-sensitive materials which are induced by accumulation of such static electric charges becomes remarkable with an increase of the sensitivity of the photographic light-sensitive materials and an increase of the processing rate thereof. Particularly, in recent years, static marks are easily generated because the photographic light-sensitive materials have high sensitivity and they are frequently subjected to severe handling such as high rate coating, high rate photographing or high speed automatic development processing, etc.
In order to remove these problems caused by static electricity, it is preferred to add antistatic agent to the photographic light-sensitive materials. However, antistatic agents generally used in other fields cannot always be used as antistatic agents for photographic light-sensitive materials, and they are subject to various restrictions characteristic of photographic light-sensitive materials. Namely, antistatic agents capable of being utilized for photographic light-sensitive materials are required to have not only an excellent antistatic property but also excellent performances, for example, they do not have a bad influence upon the photographic characteristics, such as sensitivity, fog, granularity, sharpness, etc., of the photographic light-sensitive materials, they do not have a bad influence upon the film strength of the photographic light-sensitive materials (namely, scratches are not easily formed by friction or scratching), they do not have a bad influence upon adhesion resistance (namely, surfaces of photographic light-sensitive materials are not easily adhered to each other or to the surface of other materials), they do not accelerate fatigue of the processing solutions for the photographic light-sensitive materials, they do not pollute conveying rollers, they do not deteriorate the adhesion strength between each constituent layer in the photographic light-sensitive materials, and the like. Thus, antistatic agents are subject to many restrictions in order to be useful with photographic light-sensitive materials.
One way for removing problems caused by static electricity is to increase the electric conductivity of the surface of the light-sensitive materials so that static electric charges are scattered and lost within a short time before the accumulated charges are discharged.
Accordingly, processes for improving the electric conductivity of the support of the photograhic light-sensitive materials or coated surface layers thereof have been proposed hitherto, and utilization of various hygroscopic substances or water-soluble inorganic salts, certain kinds of surface active agent, polymers, etc., have been attempted. For example, polymers as described in U.S. Pat. Nos. 2,882,157, 2,972,535, 3,062,785, 3,262,807, 3,514,291, 3,615,531, 3,753,716 and 3,938,999, etc., surface active agents as described in U.S. Pat. Nos. 2,982,651, 3,428,456, 3,457,076, 3,454,625, 3,552,972 and 3,655,387, etc., metal oxides and colloidal silica as described in U.S. Pat. Nos. 3,062,700, 3,245,833 and 3,525,621, and the like have been known.
However, many of these substances show specificity according to the kind of film support or difference of photographic constituent elements, and they produce a good result for a certain kind of film support and photographic emulsion or other photographic constituent elements, but they are useless for preventing electrification in another film support and photographic constituent elements and also have a bad influence upon the photographic properties.
On the other hand, there are many cases that they show very excellent antistatic effects, but they cannot be used because they have a bad influence upon the photographic characteristics such as sensitivity, fog, granularity, sharpness, etc., of the photographic emulsions. For example, polyethylene oxide type compounds are well known to have an antistatic effect, but they often have a bad influence upon the photographic characteristics such as an increase of fog, desensitization, deterioration of granularity, etc. Particularly, in the sensitive materials wherein both sides of the support are coated with a photographic emulsion, such as medical direct X-ray sensitive materials, it is very difficult to establish a technique of effectively giving the antistatic property without having a bad influence upon the photographic characteristics. As described above, it is very difficult to apply antistatic agents to the photographic light-sensitive materials, and the extent of their use is often restricted.
A further way of removing the problems of the photographic light-sensitive materials caused by static electricity is to lower the electricity generation of the surface of light-sensitive materials so that generation of static electricity caused by friction or contact as described above becomes small.
For example, fluorine containing surface active agents as described in British Pat. Nos. 1,330,356 and 1,524,631, U.S. Pat. Nos. 3,666,478 and 3,589,906, Japanese Patent Publication No. 26687/77, and Japanese Patent Applications (OPI) Nos. 46733/74, 32322/76, 84712/78 and 14224/79 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), have been used for the photographic light-sensitive materials for the above described purpose.
However, photographic light-sensitive materials containing these fluorine containing surface active agents have a static electric characteristic of, generally, negatively charging by various materials contacting therewith. Though it is possible to control the electricity generation caused by a rubber roller, Delrin (trade name of E. I. Dupont, formaldehyde polymer) roller, nylon bar, etc., contacting therewith so as to be small by combining them with a coating agent having a positively charging property to such materials, the fluorine containing surface active agents still have difficulty in reducing the electricity generation for all materials. For example, in the case of reducing the electricity generation for rubber, a branched static mark is generally formed by Delrin, etc., which is situated on a more positive position in the electrification series. In contrast with this, in the case of reducing electricity generation for Delrin, a spot static mark is generally formed by rubber, etc., which is situated on a more negative position in the electrification series. In order to compensate these cases, there is a process wherein the surface resistance is reduced by using high polymer electrolytes as described in British Pat. No. 1,293,189. However, they produce various side effects, for example, they deteriorate the adhesion resistance or have a bad influence upon the photographic properties. Accordingly, it is impossible to incorporate them in such an amount that a sufficient antistatic property is obtained.
Further, as a process for preventing electrification which has low dependence on the materials, that of using fluorine containing cationic surface active agents having no polyoxyalkylene moiety has been described in U.S. Pat. No. 3,850,642 and Japanese Patent Applications (OPI) 52223/73, 127974/77 and 200235/83. However, in this technique, since the electricity generation is reduced by using a combination of the fluorine containing cationic surface active agent with another surface active agent showing positive electricity generation in the electrification series, not only is the production difficult because of being affected by the coating or drying conditions, but also the electricity generation property thereof easily changes during presevation after production. In addition, it is difficult to maintain the desirable property of preventing electrification.
Moreover, these fluorine containing cationic surface active agents having no polyoxyalkylene moiety have a serious fault that, since their solubility in water or the developing solution is lower than that of the fluorine containing cationic surface active agents having a polyoxyalkylene moiety, they easily form a complex which is slightly soluble in water with an anionic surface active agent ordinarily used as a coating agent or emulsifier or dispersing agent. This causes a repellent phenomenon in the case of coating or pollution in the development processing step.